Planar optical waveguide

ABSTRACT

An embossed optical waveguide for light transmission and a method for creating a master and for generating the embossed optical waveguide therefrom. In accordance with an exemplary embodiment of the present invention, a layer of liquid polymer is exposed to energy curing radiation through a mask consisting of clear and opaque areas. The opaque areas in the mask correspond to areas in the liquid polymer which will not be exposed to the curing radiation. During exposure, the areas in the liquid polymer which are exposed through the clear areas in the mask to the curing radiation become cured, or hardened. The areas which are not exposed to the curing radiation do not become cured and subsequently are washed away with a chemical rinse. The resulting structure is a cured layer of polymer having holes pierced through it. The holes pierced through the polymer layer correspond to optical elements formed in the polymer layer. Alternatively, these optical elements can be formed in the layer of polymer after it is cured by reactive ion etching or ion beam milling. The polymer layer which has an index of refraction of 1.55 or greater is bonded to a substrate, which is preferably polypropylene, having an index of refraction of preferably 1.50 or less. Since the refractive index of air is approximately 1.0, the polymer layer is sandwiched between two layers of low refractive index material. The differences between the indices of refraction cause light projected into the polymer layer to be guided in the polymer layer by total internal reflection. Furthermore, once the optical elements have been formed in the polymer layer, it can be used as a master for generating embossments. The embossments are preferably generated by placing liquid polymer in contact with the master, curing it, and separating the cured polymer embossment from the master.

RELATED APPLICATION

[0001] This application claims priority from and the benefit of U.S.Provisional Patent Application Serial No. 60/381,325 filed May 17, 2002.

[0002] Field of the Invention

[0003] The present invention relates to an optical waveguide havingoptical elements formed therein and, more particularly, to a polymeroptical waveguide for light transmission having optical elements formedtherein for optical computing, optical processing, and light controlproviding defined optical pathways, and a method for creating a masteroptical waveguide and for producing the polymer optical waveguidetherefrom.

BACKGROUND OF THE INVENTION

[0004] It is generally known in the art that an optical waveguide can becreated by placing layers of materials in contact with each other whichhave different indices of refraction such that light focused in thelayer of material having the higher index of refraction will remain inthat layer due to total internal reflection of the light at theboundaries between the higher index of refraction material and thematerials having lower indices of refraction. There are several patentswhich teach this general concept. For example, Sugano et al., U.S. Pat.No. 4,015,893, discloses a method for creating light transmission pathson a compound semiconductor surface. Isolation zones are formed on thesurface of a substrate by plasma oxidation which causes an oxide filmhaving a different refractive index than the substrate to be selectivelyformed thereon. The refractive index of the isolation zones graduallydecreases from the boundary face between the substrate and the filmtoward the outer surface of the film. These isolation zones constitutethe light transmission paths.

[0005] Sugano et al, also disclose epitaxially growing aGaAS_(0.6)P_(0.4) compound semiconductor layer on a GaAs substrateforming the isolation zones in the GaAS_(0.6)P_(0.4) layer such that theisolation zones arrive at the GaAs substrate. The refractive index ofthe oxide film gradually decreases laterally away from theGaAS_(0.6)P_(0.4) channels such that light entering the oxide filmpropagates into the GaAS_(0.6)P_(0.4) channel.

[0006] Spillman, Jr., et al., U.S. Pat. No. 4,547,262, disclose a methodfor fabricating optical waveguides in LiTaO₃. A masking pattern is firstformed on the surface of the substrate, the substrate surface having themasking pattern thereon is immersed in benzoic acid whereby a protonexchange process occurs which increases the extraordinary component ofthe refractive index in the unmasked area of the substrate. Thesubstrate is then heated to transform the step index profile produced bythe benzoic acid reaction into a gradient index profile having a loweredvalue of refractive index at the guide surface. The unmasked, alteredareas of the substrate comprise the optical waveguides. Spillman Jr., etal. also disclose forming optical elements such as lenses, mirrors,prisms, and diffraction gratings in the planar waveguide formed by theabove-discussed method.

[0007] Suzuki et al., U.S. Pat. No. 4,983,499, disclose a method forforming a lens in a planar optical waveguide. The planar waveguide iscovered with a layer of photoresist which is exposed through a photomask and developed to form the photoresist mask. The mask has amultiplicity of separate openings and the density of openings per unitarea is continuously varied. A material such as titanium is thendeposited on the non-masked areas of the surface of the waveguide. Themasking positions of the photoresist are then removed thereby leavingonly selected areas of the waveguide covered with titanium. The titaniumis then thermally diffused into the waveguide to produce a gradientrefractive index region in the waveguide which corresponds to the lens.

[0008] In another embodiment, Suzuki et al, disclose depositing thetitanium layer onto the surface of the waveguide and depositing a layerof photoresist on top of the titanium. The photoresist is masked,exposed and developed thereby leaving openings in the photoresist layer,the density of the openings per unit area being continuously varied. Theexposed titanium is etched and the remaining photoresist is subsequentlyremoved, thereby leaving selected areas of the waveguide covered withtitanium. The titanium is then diffused into the waveguide to form agradient refractive index region which corresponds to the lens.

[0009] Although the concept of creating optical waveguides and formingoptical components in the waveguides is generally known, a need existsin the art for an optical waveguide that can be relatively easily andinexpensively produced.

[0010] The process of creating a gradient refractive index area in amaterial is not, in and of itself, new. For example, Borrelli, et al.,U.S. Pat. No. 4,403,031, disclose a method for forming optical patternsin glass by creating optical density and/or refractive index variationin porous glass. The patterns are formed by impregnating a portion ofthe porous glass with a photolyzable organometallic compound andexposing at least the impregnated portion to photolyzing light to causephotolytic decomposition of the organometallic compound to a photolyzedmetal-organic intermediate in a pattern corresponding to the exposure.As discussed above, Spillman, Jr., et al. utilize a proton exchangeprocess to increase the extraordinary component of the refractive indexin the unmasked area of a substrate. Once the substrate is heated, thestep index profile is transformed into a gradient index profile having alower value of refractive index at the waveguide surface. Suzuki, et alsupra, disclose altering the index of refraction of selected areas ofthe waveguide by thermally diffusing titanium into the waveguide toproduce a gradient refractive index region in the waveguide whichcorresponds to the lens.

[0011] None of the above prior art teaches or suggests forming anoptical waveguide from at least two polymer layers which have differentindices of refraction. Also, none of the prior art teaches or suggestscreating optical elements in a waveguide by methods similar to those ofthe present invention. Furthermore, none of the prior teaches orsuggests fabricating a master waveguide having shaped optical elementsformed therein and producing polymer optical waveguides from the master.Moreover, none of these references teach or suggest piercing ¼wavelength diameter, or smaller, holes into the surface of a polymerlayer to create a gradient refractive index lens or other opticalelement, as is taught by the present invention.

SUMMARY OF THE INVENTION

[0012] In accordance with the present invention, a planar waveguidemaster having the physical form of optical elements formed therein isproduced and polymer replicas are easily and inexpensively generatedtherefrom. This allows optical waveguides having optical componentsformed therein to be mass-produced.

[0013] In an exemplary embodiment of the present invention, a layer ofliquid energy curing polymer is exposed to ionizing radiation through amask consisting of transmitting and opaque areas. The opaque areas inthe mask correspond to areas in the liquid polymer which will not beexposed to the ionizing radiation. During exposure, the areas in theliquid polymer which are exposed through the transmitting areas in themask to ionizing radiation become cured, or hardened. The areas whichare not exposed to the ionizing radiation do not become cured andsubsequently are washed away with a chemical rinse. The resultingstructure is a cured layer of polymer having shaped holes piercedthrough it, the cured layer of polymer being bonded to a polymericsubstrate such as polypropylene. The shaped holes pierced through thepolymer layer correspond to optical elements formed in the polymerlayer. Alternatively, these optical elements can be formed in the layerof polymer, after it is cured, by reactive ion etching or ion beammilling. The formed polymer layer, which in one embodiment has an indexof refraction of approximately 1.55 or greater, can be placed in contactwith or bonded to a substrate, such as polypropylene, which having anindex of refraction, for example, of approximately 1.50 or less. Sincethe refractive index of air is approximately 1.0, the formed polymerlayer is sandwiched between two layers of low refractive index material.The polymer layer having the optical elements formed therein does nothave to be bonded to a substrate but can function as a free-standingplanar optical waveguide wherein air on both sides of the waveguidecreates the required refractive index differential. The differencesbetween the indices of refraction cause light projected into the formedpolymer layer to be guided through the formed polymer layer by totalinternal reflection. The formed polymer layer therefore functions as aplanar waveguide and the shaped holes function as optical elements inthe waveguide plane.

[0014] The formed polymer layer having the optical elements formedtherein can be used as a master from which additional polymer opticalwaveguides can be produced. For example, a replica polymer waveguide canbe produced by placing a layer of polymer in contact therewith,solidifying the polymer layer, and separating the solidified layer ofpolymer.

[0015] In accordance with another embodiment of the present invention,once the polymer master has been created, a nickel master can beproduced by electroplating the polymer master. In order to produce anembossed optical waveguide, a layer of liquid polymer is placed incontact with the master. For example, a substrate such as a layer ofpolypropylene is placed in contact with the layer of liquid polymer. Theliquid polymer can be an ionizing radiation curing material that issolidified by exposure to ultraviolet light or to an electron beam, orthe liquid polymer can solidify by a chemical reaction, such as atwo-part epoxy, urethane, or acrylic, or the liquid polymer may be athermoplastic that solidifies by cooling. After the liquid polymer hasbeen solidified by the appropriate means it becomes bonded to thesubstrate. The formed polymer waveguide is then separated from themaster. The polymer waveguide thus formed is a planar waveguide that isa negative of the form of the master.

[0016] The present invention also discloses novel methods for creatingoptical elements in the planar waveguide of the present invention. Forexample, once an optical planar waveguide has been created in accordancewith the methods of the present invention, optical elements may beformed therein by selectively altering the refractive index of thewaveguide material in particular locations by piercing holes in thewaveguide which have diameters which are generally on the order of ¼ ofthe wavelength, or less, of the light being projected into the waveguideto form gradient refractive index areas. Since the holes are small incomparison to the wavelength of light, the light interacts with thepierced area of the waveguide as having a bulk property, or averagedindex of refraction, over the pierced area. Different types of opticalelements can be created by this method.

[0017] When we refer to a “liquid polymer” or a “liquid energy curingpolymer”, we are referring to energy curing polymers (such as both UVand electron beam cured polymers), reactive polymer systems (such asepoxies, urethanes and acrylics), and thermoplastics (such aspolypropylenes, polyethylenes, amorphous PET, and acrylics).

[0018] The present invention further provides replicated polymerwaveguide planar optical films for document authentication and theprevention of counterfeiting.

[0019] These advantages of the present invention will be apparent fromthe foregoing discussion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Many aspects of the invention can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale. Moreover, in the drawings, like referencenumerals designate corresponding parts throughout the several views.

[0021]FIG. 1 illustrates a perspective view of the planar opticalwaveguide of the present invention in accordance with an examplaryembodiment.

[0022]FIG. 2 illustrates a cross-sectional view of the optical waveguideof FIG. 1 showing optical element 6 formed therein.

[0023]FIGS. 3a-3 d illustrate top plan views of conventional lensesformed of solid material and their equivalents formed as air slots inthe optical waveguide of the present invention.

[0024]FIG. 4 illustrates a cross-sectional view of the optical waveguideof the present invention in accordance with an alternative embodiment.

[0025]FIG. 5a illustrates a cross-sectional view of the opticalwaveguide of the present invention in accordance with anotherembodiment.

[0026]FIG. 5b illustrates a cross-sectional view of a multi-layer,dielectric mirror comprised in the optical waveguide of FIG. 5a.

[0027]FIG. 6a illustrates a cross-sectional view of the opticalwaveguide of the present invention having an optical element formedtherein in accordance with one embodiment of the present invention forcreating the optical elements and the optical waveguide.

[0028]FIG. 6b illustrates an expanded cross-sectional view of theoptical waveguide of FIG. 6a wherein the optical element formed in theoptical waveguide is a converging lens.

[0029]FIG. 6c illustrates an expanded cross-sectional view of theoptical waveguide of FIG. 6a wherein the optical element formed in theoptical waveguide is a diverging lens.

[0030]FIG. 7 illustrates a cross-sectional view of the optical waveguideof FIG. 1 showing optical elements 6, 14 and 18 formed therein.

[0031]FIG. 8 illustrates' a plan view of a spectroscope.

[0032]FIG. 9 illustrates a perspective view of the optical waveguide ofthe present invention having a spectroscope formed therein.

[0033]FIG. 10 illustrates a plan view of the diffraction grating of thespectroscope shown in FIG. 9.

[0034]FIG. 11 illustrates a perspective view of obstructions which canbe formed in the optical waveguide of the present invention and whichaffect the propagation of light projected into the optical waveguide.

[0035]FIG. 12 illustrates an alternative embodiment for the obstructionsshown in FIG. 11 wherein the obstruction is a multi-layer dielectricmirror.

[0036]FIG. 13 illustrates a cross-sectional view of the projectionscreen of the spectroscope formed in the optical waveguide and shown. inFIG. 9.

[0037]FIG. 14a illustrates a plan view of an optical element formed inthe optical waveguide of the present invention which is preceded andfollowed by anti-reflection structures.

[0038]FIG. 14b illustrates an enlarged plan view of the anti-reflectionstructures shown in FIG. 14a.

[0039]FIG. 15 illustrates an alternative embodiment for creating theanti-reflection structures.

[0040]FIG. 16 illustrates one embodiment of the present invention forcreating a reflective surface in theoptical waveguide by selectivelyaltering the refractive index in certain areas of the optical waveguide.

[0041]FIG. 17 illustrates one embodiment for confining the path of lightwithin the optical waveguide of the present invention by selectivelyaltering the refractive index in certain areas of the optical waveguide.

[0042]FIG. 18 illustrates a plan view of another embodiment forconfining the path of light within the optical waveguide by altering therefractive index of light in certain areas of the optical waveguide.

[0043]FIG. 19 illustrates a plan view of one embodiment of the opticalwaveguide of the present invention having an optical element formedtherein which can function as a beam splitter or as a combiner.

[0044]FIG. 20 illustrates a plan view of the optical waveguide of thepresent invention having an optical demultiplexer formed therein.

[0045]FIG. 21 illustrates the hole-piercing technique of the presentinvention.

[0046]FIG. 22 illustrates a cross-section of a master embossed from thelayer shown in FIG. 21 having holes pierced therein.

[0047]FIGS. 23 and 24 illustrate the process for creating a master inaccordance with the present invention and for generating embossmentstherefrom.

[0048]FIG. 25 illustrates an isometric view of a further embodiment ofthe present invention in which planar optics are incorporated intopolymer substrates to form a counterfeit resistant document substrate.

DETAILED DESCRIPTION OF THE INVENTION

[0049]FIG. 1 illustrates the optical waveguide 1 of the presentinvention. Optical elements 6, 14 and 18 represent examples of the typesof optical elements that can be formed in the optical waveguide 1. Light2, 12, 13 projected into the light control device is manipulated by theoptical elements in a predetermined manner. The optical elements aredesigned to receive light from a particular direction and to control thelight in accordance with their optical properties. Therefore, theoptical waveguide 1 can be created such that light projected into theoptical waveguide from any predetermined direction will be received byan optical element and controlled in accordance with the opticalcharacteristics of the particular optical element. The optical elementthat receives the light projected into the device will manipulate thelight and transmit the light to other optical elements that furthermanipulate the light in accordance with their optical characteristics.

[0050] The optical waveguide 1 of FIG. 1 is typically comprised of afirst layer of material 3 that has a relatively high index of refractionand a substrate 8 that has a relatively low index of refraction. Thelight 2 projected into layer 3 will be optically guided in layer 3 bytotal internal reflection which results from layer 3 being locatedbetween two mediums with low indices of refraction, i.e., substrate 8and air. The differences between the indices of refraction willdetermine the critical angle at which total internal reflection withinlayer 3 occurs. It is also possible to cover the top surface of layer 3with a relatively low refractive index material as an alternative to airin addition to covering the bottom surface with low refraction indexmaterial.

[0051] When referring to polymer layer 3 as having a relatively highindex of refraction and substrate 8 as having a relatively low index ofrefraction what is meant is the index of refraction of the polymer layer3 relative to the index of refraction of substrate 8.

[0052] In an exemplary embodiment layer 3 is a layer of polymer havingan index of refraction of approximately 1.55 or greater. Substrate 8 isa polymer that has in index of refraction of approximately 1.50 or less.The refractive index of air is 1.0. The differences between the indicesof refraction of layer 3 and substrate 8 will determine the criticalangle for total internal reflection. Since the direction of light 2projected into the waveguide can be controlled such that it is projectedsubstantially parallel to the plane of layer 3, the relative differencebetween the refractive indices of layer 3 and substrate 8 of 0.05 ismore than sufficient to cause total internal reflection.

[0053] Polymer layer 3 can be formed by taking a layer of liquid energycuring polymer and exposing it to patterned ionizing radiation. Opticalelements 6, 14 and 18 are areas of polymer that are not exposed to theionizing radiation. A mask (not shown) consisting of transmitting andopaque areas is used to mask certain areas of liquid polymer layer 3during exposure to ionizing radiation. The opaque areas in the maskcorrespond to the areas in the liquid polymer that are not exposed toionizing radiation. During exposure, the areas in the liquid polymerthat are exposed to ionizing radiation become cured, or hardened. Theareas that are not exposed do not become cured and are subsequentlywashed away with a chemical rinse. The resulting structure is a curedlayer of polymer having holes pierced through it. The shapes of theholes correspond to the shapes of the opaque areas in the mask. As shownin FIG. 2, these shapes are pierced through layer 3 but not substrate 8.

[0054] Suitable examples of energy-cured polymers include polymers curedby both ultraviolet and electron beam cured systems. Thus, for example,the polymer layer 3 may be formed or cured by selectively exposing it toultraviolet (UV) light. Alternatively, the optical elements can beformed in a layer of energy-cured polymer 3 by reactive ion etching orion beam milling. The technique used to create an optical elementdepends on the desired shape of the optical element. Additionally,polymer layer 3 can be formed of reactive polymer systems, such asepoxies, urethanes and acrylics, by forming or solidifying polymer layer3 by chemical reaction. Further, polymer layer 3 can consist of athermoplastic polymer that is formed or solidified by cooling. Suitablethermoplastic polymers include polypropylene, polyethylene, amorphousPET and acrylics.

[0055] Optical element 6 of FIG. 1 is a hole shaped like a planarconcave lens. Since light passing through the lens is propagating from ahigh refractive index region into a low refractive index region (air),the lens behaves like a conventional planar convex lens wherein lightpropagates from a low refractive index region (air) into a highrefractive index region (the lens). FIGS. 3a-3 d illustrate conventionallenses 20, 23, 25 and 27 formed of solid material and their equivalentsformed as slots of air (or low refractive index material) 21, 24, 26, 28in the polymer layer 3. Optical element 18 in FIG. 1 is a right-angleprism wherein the angle of the surface upon which light 13 is impingingis sufficient to cause the light to be totally reflected into polymerlayer 3. Light 13 impinges on the upper surface of layer 3 in adirection normal to the surface. Optical element 14 is also aright-angle prism that receives light 12 directed at the bottom surfaceof polymer layer 3 in a direction normal to the surface. The light 12 istotally reflected into polymer layer 3 and guided through the layer bytotal internal reflection. In a similar manner, optical elements canalso be formed in layer 3 which reflect light back out of the opticalwaveguide as discussed below with respect to FIG. 9, for example.

[0056]FIG. 2 illustrates a cross-sectional view of the optical waveguideof FIG. 1 having lens 6 formed therein. Preferably, the optical elementsformed in layer 3 extend through layer 3 and are bottomed out againstsubstrate 8. Alternatively, a controlled gap (not shown) can be createdbetween the bottom of the optical elements and substrate 8. When lightpropagating through layer 3 exits the polymer into air at lens 6, asmall amount of the light will be drawn into substrate 8 since thesubstrate 8 has a higher refractive index than air. By creating acontrolled gap of polymer between optical element 6 and substrate 8, thelight will see an average refractive index of the refractive indices ofair and the polymer. By controlling the thickness of this gap to producean average refractive index slightly higher than the refractive index ofsubstrate 8 but lower than the refractive index of layer 3, the amountof light drawn into the substrate 8 will be minimized.

[0057]FIG. 4 illustrates a cross-sectional view of an alternativeembodiment of the optical waveguide 1 of the present invention (onlyshowing optical element 6) wherein a highly reflective metalizationlayer 5, such as aluminum or silver, is formed between substrate 8 andpolymer layer 3. Any light which propagates toward the metalizationlayer 5 will be reflected and, therefore, remain in the polymer layer 3.A possible disadvantage to incorporating a metalization layer into thestructure is that some of the light energy may be absorbed by themetalization layer 5 upon reflection.

[0058]FIG. 5a illustrates a cross-sectional view of another embodimentof the optical waveguide 1 wherein a multilayer dielectric mirror 7 isdeposited on the substrate 8. The multi-layer dielectric mirror 7 servesas an interference barrier between the polymer layer 3 and the top highrefractive index layer of the multi-layer dielectric mirror 7. When thelight propagating in polymer layer 3 exits into the air at opticalelement 6, the multi-layer dielectric mirror 7 will reflect the light sothat it continues to propagate across the air gap, and into polymerlayer 3. FIG. 5b illustrates an enlarged cross-sectional view of themultilayer, dielectric mirror 7. Although the dielectric mirror willreflect light of a particular wavelength, in accordance with the spacingand width of the layers, very little energy is lost to absorption sincethe mirror is nonconductive. A Fabry-Perot interference filter structurecan be used for high efficiency reflection.

[0059]FIG. 6a illustrates a cross-sectional view of an alternativeembodiment for creating the optical elements of the present inventionthat are formed in polymer layer 3. In this embodiment, optical element32 is created by piercing very small holes in polymer layer 3 which havediameters that are generally on the order of ¼ of the wavelength of thelight or less. Since the holes are small in comparison to the wavelengthof light, the light reacts with the pierced area of the material ashaving a bulk property, or averaged index of refraction, over thepierced area. Thus, the index of refraction of a particular area oflayer 3 can be altered by piercing tiny holes in layer 3. In areas wherethe numbers of holes is greater, the refractive index will be lower, inareas where there are fewer holes, the index of refraction will behigher.

[0060]FIG. 6b is an expanded cross-sectional view of optical element 32.The number of holes 34 pierced through polymer layer 3 is greatest atthe center of optical element 32 and it decreases toward the outer edgesof optical element 32. Therefore, the index of refraction will be lowestin the center of the altered area and it will increase toward the outeredges of the altered area. Light propagating through optical element 32in a direction perpendicular to the plane of the Figure will movefastest in the low refractive index region, thereby causing the light tobe refracted into the high refractive index region. The optical element32 of FIG. 6b is a diverging lens because the light diverges away fromthe center of the altered area as it propagates through the opticalelement 32 in a direction substantially perpendicular to the plane ofthe Figure.

[0061]FIG. 6c illustrates a cross-sectional view of an optical element33 that is a converging lens. The number of holes pierced throughpolymer layer 3 is greatest at the outer edges of optical element 33 anddecreases toward the center of optical element 33. Therefore, the indexof refraction will be highest at the center of the optical element andit will decrease toward the outer edges of the optical element. Lightpropagating through optical element 33 of FIG. 6c in a directionsubstantially perpendicular to the plane of the Figure will convergefrom the low refractive index region (outer edges) into the highrefractive index regions (center) thereby causing the optical element tobehave like a converging lens.

[0062] One advantage of using optical elements of the type shown inFIGS. 6b and 6 c is that light propagating from the high refractiveindex region of polymer layer 3 into the optical element never entersthe open air and, therefore, never has an opportunity to propagate outof polymer layer 3. Furthermore, the optical element can be created suchthat the index of refraction over the pierced area of the polymer layer3 is always higher than the index of refraction of the substrate 8.Therefore, the light propagating through the optical element will not bedrawn into the substrate 8.

[0063]FIG. 7 illustrates a cross-sectional view of the optical waveguideof FIG. 1 having optical elements 6, 14 and 18 formed therein. Opticalelements 14 and 18 receive light and project it into polymer layer 3.These elements are designed such that the difference between the indexof refraction of air and layer 3 causes light impinging on the elementsto be reflected into layer 3 as shown.

[0064]FIG. 8 illustrates a plan view of a spectroscope that can beincorporated into the optical waveguide 1 of the present invention. Alight source 40 projects light onto lens 41 that focuses the light ontoobstructions 42. The obstructions 42 are separated by a small distancethat forms a slit 46 between the obstructions 42. The slit 46 controlsthe width of the spectral lines formed by curved diffraction grating 43.Diffraction grating 43 is reflective and has a light-absorbing surface45 behind it that absorbs any light not reflected by diffraction grating43. The diffraction grating 43 reflects the spectrum of light onto aprojection screen 44 and focuses the different wavelengths of light atspatially separated points on screen 44. Diffraction grating 43 can bemetallized to increase its efficiency. Screen 44 may be a metallizedsurface to reflect the spectrum out of the plane of the waveguide or itcan incorporate scattering materials or microstructures.

[0065]FIG. 9 illustrates the optical waveguide of the present inventionhaving one embodiment of a spectroscope formed therein. A right-angleprism 51 receives light 50 projected onto the bottom surface of thepolymer layer 3. Prism 51 deflects the light onto obstructions 42 whichhave a slit between them. The slit controls the width of the spectrallines formed by curved diffraction grating 43. The diffraction grating43 reflects the spectrum of the light onto screen 44 and focuses thedifferent colors of the spectrum at spatially separated points on thescreen 44. The screen 44 can be a right-angle prism that has a roughenedsurface such that it functions as a diffuse reflector. Screen 44reflects the spatially separated colors 53 out of the optical waveguide1. All of the spectral analysis of the light occurs in polymer layer 3.All of the optical components may be formed by selectively curingpolymer layer 3, by reactive ion etching or ion beam milling, or byforming the optical components by replicating a polymer against a mastertool and separating the cured replica from the master.

[0066] The holes formed in polymer layer 3 which may correspond tolenses or prisms, for example, have geometries designed to create thedesired optical characteristics, as described above with reference toFIGS. 1-6 c. Obstructions 42 reflect the light that does not passthrough the slit. The obstructions can be made reflective by depositinga reflective material onto the surface of the obstructions.Alternatively, the obstructions 42 can be multi-layer dielectric mirrorshaving alternating layers of high and low refractive indices, asdescribed in detail below with respect to FIG. 12. The obstructions 42can also be total internal reflection prisms which reflect all of thelight not passing through the slit back up out of polymer layer 3, asshown in FIG. 11. The obstructions 42 can also be filled with a lightabsorbing material, such as a pigmented polymer, to absorb the lightthat does not pass through the slit.

[0067] Diffraction grating 43 can be made reflective by depositing areflective material such as aluminum thereon or by forming thediffraction grating of layers of alternating high and low refractiveindices such that it behaves like a dielectric mirror as discussedabove. A plan view of the diffraction grating 43 is shown in FIG. 10.The light absorbing surface 45 may be a light trap formed by reactiveion etching the cured layer of polymer such that a non-uniform etch inthe polymer results. The etching process creates stalactite-typestructures that have high length-to-width or aspect ratios. Thesestructures are then covered with a reflective material. The high aspectratios and the non-uniformity of the structures cause light entering thelight trap to be reflected within the light trap until substantially allof the light has been absorbed. Diffraction grating 43 has a curvedsurface with grooved shapes formed therein. The grooved shapes have ablaze angle 55 that is designed for the period spacing of thewavelengths of light that are to be focused on screen 44.

[0068] When it is desirable to perform a spectrum analysis on broadbandlight, the obstructions 42 shown in FIG. 11 may be used to form theslit. Light 61, 63 which does not pass through the slit is reflectedback out of the polymer layer 3 as indicated by numerals 62 and 64. Whennarrow band light, such as light generated by an LED, is being projectedinto the optical waveguide 1, obstructions 42 and diffraction grating 43can be comprised of multilayer dielectric mirrors that consist ofalternating layers of high and low refractive indices.

[0069]FIG. 12 illustrates one of the obstructions 42 comprised of layersof high refractive index material separated by air slots having arefractive index of 1.0. The width of the layers can be substantially ¼of the wavelength of light being projected onto the obstructions,depending on the need for creating constructive interference ordestructive interference effects. Therefore, all of the light impingingon the obstructions will be reflected in accordance with the reflectiveproperties of conventional dielectric mirrors. At each interface of alow and a-high refractive index layer, the light will be reflected inphase with the incoming light, thereby creating constructiveinterference and total reflection. The air slots may be created bymasking areas in which it is desirable to have air prior to exposing theliquid polymer to ionizing radiation. The unexposed areas are thenrinsed away leaving air slots in the polymer layer 3 which forms thedielectric mirrors. Alternatively, the air slot mirror microstructurescan be plasma beam etched or reactive ion etched into polymer layer 3. Amaster pattern can alternatively be created by conventional UV or deepx-ray exposure of photoresist followed by strong anisotropicdevelopment. The optical pathlength through each layer of the air slotmicrostructures should be substantially equal to half the wavelength ofthe light in that medium to obtain maximum reflectivity Conventionaldielectric mirrors are only desirable when narrow band light is to beanalyzed by the spectroscope. When broadband light is to be analyzed, itis desirable to coat the obstructions 42 and the diffraction grating 43with a reflective material such as aluminum to give them the desiredreflective properties.

[0070]FIG. 13 illustrates a cross-sectional view of one embodiment ofprojection screen 44 formed in polymer layer 3. In this embodiment thescreen 44 consists of a right-angle prism having a roughened surfacesuch that the light reflected onto the screen by the diffraction gratingis diffusely reflected back out of the optical waveguide as indicated byarrows 65.

[0071]FIG. 14a illustrates an optical element 70 formed in polymer layer3 of the optical waveguide shown in FIG. 1. The optical element 70 ispreceded and followed by antireflection structures 75 and 76,respectively. The anti-reflection structures 75 and 76 eliminatereflection that will otherwise occur at the interfaces of air andpolymer. The multi-layer antireflection structures are comprised ofalternating layers of high and low refractive indices, as shown in FIG.14b. The scored areas 81 correspond to the polymer layer 3. The clearareas 82 correspond to slots of air created in the polymer layer 3. Theoptical pathwidths of the slots of air and layers of polymer 81 are ½ ofthe wavelength of light being used. Any light reflected at theinterfaces of air and polymer will be out of phase 90° with respect tolight impinging on the interface. Therefore, the incoming light willdestructively interfere with any light reflected at the interfaces,thereby eliminating all reflection.

[0072]FIG. 15 illustrates an alternative embodiment for theantireflection structure of the present invention. The hole-piercingtechnique described above with reference to FIGS. 6a-6 c is used tocreate a gradient refractive index in the region of polymer precedingand following the optical element 70. The number of holes piercedthrough the polymer increases as the distance from the optical element70 decreases. Therefore, the refractive index of the polymer graduallydecreases as the light approaches optical element 70, thereby decreasingreflection at the interface of the optical element 70 and the polymer.

[0073]FIG. 16 illustrates how the hole-piercing technique can be used tocreate a reflective surface as opposed to the antireflection structureof FIG. 15. Regions 92 in the polymer represent areas in which holeshave been pierced through the polymer layer to create regions havinglower refractive indices. Regions 91 represent unpierced regions ofpolymer which have higher indices of refraction. The width of thepierced regions and is equal to ¼ of the wavelength of the light 90 asmeasured in the lower refractive index of the pierced regions. Thespacing between the pierced regions, or the thickness of the unpiercedregions, is equal to ½ of the wavelength of the light 90 as measured inthe higher refractive index of the unpierced regions. The reflectormicrostructure of FIG. 16 behaves like a multilayer dielectric mirrorwherein light is reflected at each interface of the high and lowrefractive index layers in phase with the light impinging on theinterfaces, thereby creating constructive interference and reflection.This hole-piercing technique is particularly suitable for creatingreflective surfaces in the optical waveguide when narrow-band light isbeing analyzed by the optical waveguide.

[0074] Once a cured layer of polymer has been created which contains anyof the above-mentioned optical elements or other structures, areplication master can be created using conventional nickelelectroforming or by energy curing liquid polymer is placed in contactwith the cured layer of polymer. The cured layer of polymer and theliquid polymer are then exposed to ionizing radiation which hardens theliquid polymer. When the two layers of cured polymer are separated, thereplica represents a master from which additional polymer opticalwaveguides can be produced. Accordingly, the present invention allowspolymer optical waveguides to be mass produced.

[0075]FIGS. 17 and 18 illustrate top plan views of waveguide channelsfor guiding light within the plane of a polymer layer 94 in phasecoherence. The surface of polymer layer 94 is pierced with holes 97having diameters which are small in comparison to the wavelength of thelight (less than one quarter wavelength) by using the hole piercingtechnique described above. The unpierced area of the polymer 95constitutes a waveguide channel which has a high refractive index. Thenumber of holes pierced through the polymer layer 94 increases withincreasing distance form the center of the waveguide channel. Therefore,the index of refraction of the waveguide gradually decreases toward theouter edges of the waveguide. As light waves 93 and 96 propagate intothe waveguide from the directions shown, the light waves move from theregions of high refractive index into the regions of low refractiveindex. As the light waves move into the regions of low refractive index97 the light waves gradually refocus into the high refractive indexregion. As the light waves pass through the high refractive index regioninto the low refractive index region, the light waves are once againrefocused into the high refractive index region. By providing a gradientrefractive index in the manner shown, the light waves will propagatethrough the waveguide in phase coherence.

[0076]FIG. 18 shows an alternative embodiment for guiding light withinthe plane of the optical waveguide. A gradient refractive index iscreated by piercing slots 103 through the polymer layer 99. The width ofthe slots is on the order of less than one quarter of a wavelength oflight. The number of slots in the polymer layer increases withincreasing distance from the center of the waveguide, thereby creating agradient refractive index. Light waves 101 and 102 propagate through thewaveguide in phase coherence in the manner described above with respectto FIG. 17. The slots may be created by masking the liquid polymerduring exposure to curing radiation to selectively cure certain areasand then by rinsing away the uncured areas. Alternatively, the slots maybe created by ion beam milling.

[0077] The waveguides of FIGS. 17 and 18 operate in a manner analogousto fiber optics. However, the waveguides of FIGS. 17 and 18 representstructures which can be embossed from a master whereas fiber optics mustbe individually created.

[0078]FIG. 19 illustrates in plan view an example of one type ofembossed structure which can be created using either of the waveguidechannels of FIGS. 17 and 18. Embossed structure 105 can be a splitter ora combiner depending on the direction in which the light is propagating,i.e., depending on how it is being utilized. When light is propagatingfrom waveguide channel 107 into bifurcated waveguide channels 109, thestructure operates as an optical splitter which sends all frequencies oflight being carried by waveguide channel 107 to each of the bifurcatedwaveguide channels 109. At each bifurcation, the angle of bifurcationmust be extremely small so that the energy of the light is evenlydistributed to each waveguide channel. When light is propagating fromthe bifurcated waveguide channels into waveguide channel 107, the lightwill be combined and the structure operates as an optical combiner.

[0079]FIG. 20 illustrates a demultiplexer which utilizes the waveguidechannels of FIGS. 17 and 18. Light 111 propagating through waveguidechannel 112 impinges on the diffraction grating 114 which spatiallyseparates the frequencies of light. The different frequencies of lightare then focused by lens 15 at spatially separated points. A separatewaveguide channel is located at each point to receive a particularfrequency of light.

[0080]FIG. 21 illustrates the hole-piercing technique of the presentinvention. After polymer layer 3 of FIG. 1 has been cured by exposure tocuring radiation such as ultraviolet light and the optical elements havebeen formed therein by masking during exposure, holes are pierced in thehardened polymer in areas where it is desirable to create regions havinggradient refractive indices. A mask of chrome spots 120 is formed on thesurface of the polymer by electron beam lithography. Electron beamlithography allows features as small as 180 manometers to be formed onthe polymer. Reactive ion etching or ion beam milling is then used toetch holes 122 into the polymer.

[0081]FIG. 22 illustrates a cross-section of a master 123 embossed fromthe etched polymer layer 3 shown in FIG. 21. The master 123 is producedby first pouring liquid polymer (not shown) over hardened polymer layer3 of FIG. 21 and then exposing the liquid polymer to ultraviolet light.Posts of hardened polymer 125 are formed which have diameters which aregenerally less than one quarter of the wavelength of light. FIG. 6brepresents a cross-section of an embossment created by pouring liquidpolymer over the master shown in FIG. 22, exposing it to ultravioletlight, and separating the embossment from the master.

[0082]FIGS. 23 and 24 illustrate the process for creating a master. Themasking and exposure techniques discussed above are first used toproduce a cured layer of polymer 131 having optical elements 138, 140and 141 formed therein. Polymer layer 131 is preferably bonded to asubstrate 130 such as polyester which gives the structure mechanicalstability. A variety of techniques can be used to create the opticalelements 138, 140 and 141. Some of the optical elements can be formed bysimply masking the liquid polymer during exposure to curing radiationand then rinsing away the uncured areas of the polymer after theexposure step. It may be necessary to use other techniques to createsome of the other optical elements due to their geometries. For example,once the polymer layer 131 has been cured, optical elements can beformed therein by covering the polymer layer 131 with a layer ofphotoresist (not shown), exposing and developing certain areas of thephotoresist layer, and using reactive ion etching or ion beam milling toetch the particular optical element into the polymer layer. As discussedabove, it may be necessary to deposit a chrome mask (not shown) on thesurface of cured polymer layer 131 and then use ion beam milling to etchthe polymer away in the unmasked areas of the cured polymer 131. Inshort, the technique used to create a particular optical element willdepend on the geometry of the optical element. Generally, the opticalelements will be created by the simplest and most economical meanspossible. Furthermore, mastering need not occur in a curable polymer.Other materials, such as quartz or silicon can be processed with maskingand reactive ion etching or ion beam milling to create the original.This piece or replicas of it in polymer or nickel, for example, then canfunction as the master.

[0083] Once the optical elements have been formed, a layer of liquidpolymer 133 is placed in contact with cured polymer layer 131 as shownin FIG. 23. A substrate 135, preferably polypropylene, is placed incontact with liquid polymer 133 and the entire structure is exposed tocuring radiation such as ultraviolet light which causes liquid polymerlayer 131 to become cured and bond to substrate 135. The structurecomprised of substrate 135 and cured polymer layer 133 is then separatedfrom the structure comprised of substrate 130 and polymer layer 131. Thestructure comprised of substrate 135 and cured polymer layer 133, whichis shown in FIG. 24, may be used as a master from which embossed opticalwaveguides can be generated. It is also possible to use the structureshown in FIG. 23 comprised of layers 130 and 131 as the master if thefeatures formed in layer 131 are negatives of the features desired to beformed in the embossed optical waveguide. A metal master can be producedfrom the structure shown in FIG. 24 by electroplating the structure witha metal such as nickel. Once the master, shown in FIG. 24, has beenproduced, an embossed optical waveguide can be generated therefrom bythe same method discussed above with respect to FIG. 23. A layer ofliquid polymer (not shown) is placed in contact with the master and asubstrate, preferably polypropylene, is placed in contact with theliquid polymer. The entire structure (not shown) is then exposed tocuring radiation such as ultraviolet light which causes the liquidpolymer to harden and bond to the substrate. The embossed opticalwaveguide is then separated from the master. Alternative replicationmethods, such as compression molding and injection molding of polymermaterials, can also be used.

[0084] In summary, an optical waveguide having optical elements andother optical structures formed therein can be created by the methodsdiscussed above which will analyze light in a predetermined manner. Oncethe optical elements and structures are formed in the waveguide, anegative of the device is produced. This negative is a master of thelight control device from which replicas can be readily made by avariety of means. Alternatively, the negative can be electroplated toproduce a metal master.

[0085] Also, the optical elements formed in the initial opticalwaveguide can be negatives of the elements to be formed in the embossedoptical waveguide such that the embossed optical waveguide can begenerated directly from the initial optical waveguide. The initialoptical waveguide can be electroplated to create a metal master fromwhich the optical waveguide replicas can be produced.

[0086] Therefore, it is not necessary to individually form the opticalelements of each optical waveguide. Either during or after production ofthe embossments, subsequent layers of material can be added to theembossment to give the embossment the desired optical qualities andmechanical stability. Preferably, a layer of polypropylene is bonded tothe embossed optical waveguide. However, any material which is suitablefor use with the present invention and which has the desired opticalproperties can be used for this purpose. If the replicated opticalwaveguide is mechanically stable, then it may not be necessary to addadditional layers or toprovide a substrate.

[0087] As illustrated in FIG. 25, the planar optics of the presentinvention can also be incorporated into polymer substrates for creatingsecure documents. For example, a planar optic system that collectsincident light illuminating the surface of a document can be directedinto a waveguide core and focused to a smaller area before being emittedback out through the surface of the document. This geometricalconcentration of the light results in an increase in its intensity,producing an effect similar to embedding a light source in the documentat that location. The geometrical concentration is a constant factor, sothe region of emission will appear to be substantially brighter than thesurrounding document under a wide range of lighting conditions. Otherimage transfer, image scrambling, and illumination control can beaccomplished by suitable collection, waveguiding, and emission elementsincorporated into document substrates. These optical systems can beembedded entirely within a polymer system, rendering them difficult orimpossible to disassemble to produce tooling to create counterfeitstherefrom.

[0088] Furthermore, these optical systems can be designed to interactwith printed or metallized patterns added to the outer surfaces of thematerial such that the presence of a printed pattern, for example causesfrustrated total internal reflection (and subsequent disconnection ofthe light from the following optical system elements) while the absenceof a printed pattern enables connection of the light to subsequentoptical system elements by total internal reflection. The contactpattern of a fingerprint could be substituted for a printed pattern toenable interaction of the optical system with a user's fingerprint foridentification, authentication, and verification functions. In a similarmanner a metallization pattern can be used to enable opticalinterconnections that would not be present without the metallizationpattern or with an altered or different pattern. Additionally, awaveguide planar optic system according to the subject invention can bedesigned and embedded in the substrate of a credit card or other cardbearing an embossed pattern of numbers, symbols, or characters such thatthe embossment of the card modifies the output pattern or properties ofthe waveguide system in a manner corresponding to the embossedinformation, such as by breaking specific waveguide connections. Theauthenticity of such a card can then be verified by checking theembossed information against the waveguide system properties. If the twodon't match then the card has been tampered with, such as by alterationof the embossed numbers on the card.

[0089] The present invention is not limited to the types of opticalelements and structures which can be formed in the optical waveguide.The techniques described above for forming the optical elements andstructures in the slab waveguide can be used to create optical elementsand structures having virtually any type of geometry. Also, the presentinvention is not limited with regard to the types of materials which canbe used to create the initial waveguide or the subsequent embossments.Any materials which have the desired optical as well as mechanicalproperties can be used to create the light control device of the presentinvention. Furthermore, although the soft embossing process ispreferable for replicating the optical waveguides, it is also possibleto use a hard embossing process, such as extrusion embossing, togenerate the embossments.

We claim:
 1. An optical waveguide comprising a first polymer layerhaving at least one optical element formed therein for operating onlight in a predetermined manner, said first polymer layer having atleast two sides and a second polymer layer having at least two sideswherein one of said at least two sides of said first polymer layer isdisposed adjacent to one of said at least two sides of said secondpolymer layer, said first polymer layer having a first index ofrefraction, said second polymer layer having a second index ofrefraction, said first index of refraction being higher than said secondindex of refraction, wherein light projected into said first polymerlayer in a direction substantially parallel to said first and secondsides of said first polymer layer will be guided through said firstpolymer layer by internal reflection.
 2. An optical waveguide accordingto claim 1 wherein said at least one optical element creates a localmodification in the refractive index of said first polymer layer, saidlocal modification of the refractive index of said first polymer layercausing light impinging on said at least one optical element to beoperated on in the predetermined manner by said at least one opticalelement.
 3. An optical waveguide according to claim 2 wherein said atleast one optical element is a prism.
 4. An optical waveguide accordingto claim 3 wherein said at least one optical element is a reflector. 5.An optical waveguide according to claim 2 wherein said at least oneoptical element is a converging lens.
 6. An optical waveguide accordingto claim 2 wherein said at least one optical element is a diverginglens.
 7. An optical waveguide according to claim 1 having at least twooptical elements which cooperate as an optical system to operate onlight projected thereon.
 8. An optical waveguide according to claim 1wherein there are a plurality of optical elements formed in said firstpolymer layer and wherein said plurality of optical elements cooperateas a spectroscope to spatially separate light projected thereonaccording to frequency.
 9. An optical waveguide according to claim 1,wherein said first polymer layer has a plurality of optical waveguidechannels and a plurality of optical elements formed therein to form anoptical system.
 10. An optical waveguide according to claim 1 whereinsaid first polymer layer has at least one optical waveguide channelformed therein wherein light projected into said at least one opticalwaveguide channel is restricted by said optical waveguide channel suchthat the light projected into said optical waveguide channel propagatesin phase coherence.
 11. An optical waveguide according to claim 10wherein said first polymer layer has a plurality of optical waveguidechannels and a plurality of optical elements formed therein wherein saidplurality of optical waveguide channels and optical elements cooperateto form an optical demultiplexer.
 12. An optical waveguide according toclaim 10 wherein said first polymer layer has a plurality of opticalwaveguide channels formed therein and wherein said optical waveguidechannels comprise an optical splitter.
 13. An optical waveguideaccording to claim 10 wherein said first polymer layer has a pluralityof optical waveguide channels formed therein and wherein said opticalwaveguide channels comprise an optical combiner.
 14. An opticalwaveguide according to claim 1 wherein said optical waveguide is anembossment generated from a master.
 15. An optical waveguide accordingto claim 4 wherein said reflector is a multi-layer dielectric mirror.16. An optical waveguide according to claim 5 wherein said converginglens is a gradient refractive index lens.
 17. An optical waveguideaccording to claim 6 wherein said diverging lens is a gradientrefractive index lens.
 18. An optical waveguide according to claim 1wherein a third polymer layer is placed in contact with one of said atleast two sides of said first polymer layer not in contact with said oneof said at least two sides of said second polymer layer, said thirdpolymer layer having an index of refraction lower than said first indexof refraction.
 19. A method for creating an optical waveguide, saidmethod comprising the steps of: creating a waveguide master having thegeometrical form of at least one optical element formed therein;generating an embossed optical waveguide from said master, said embossedoptical waveguide being a negative of said master, said embossed opticalwaveguide having at least one optical element formed therein whichcorresponds to and is a negative of the geometrical form of said atleast one optical element formed in said master, said embossed opticalwaveguide comprised of a polymer material, said polymer material havinga first index of refraction, wherein said at least one optical elementis formed in said polymer material, wherein said at least one opticalelement formed in said polymer material creates a local modification ofthe refractive index of said polymer material, wherein said localmodification of the refractive index of said polymer material causeslight impinging on said at least one optical element formed in saidpolymer material to be operated on in a predetermined manner by said atleast one optical element formed in said polymer material.
 20. A methodfor creating an optical waveguide according to claim 19, furtherincluding the step of: bonding a substrate to said polymer material,said substrate having known optical and mechanical characteristics, suchthat when light projected into said embossed optical waveguide impingeson said substrate it is reflected such that it continues to propagate insaid embossed optical waveguide.
 21. A method for creating an opticalwaveguide according to claim 19 wherein said step of creating saidmaster comprises the step of exposing a layer of liquid photopolymer tocuring radiation through a mask, wherein the mask controls the exposureof said liquid photopolymer such that certain parts of said liquidphotopolymer become cured and certain parts of said liquid photopolymerremain uncured, wherein the uncured parts are subsequently removed tothereby form said at least one optical element in said master.
 22. Amethod for creating an optical waveguide according to claim 21 whereinsaid step of creating said master further comprises the step ofreactively ion etching certain parts of said cured photopolymer to formadditional optical elements therein.
 23. A method for creating anoptical waveguide according to claim 21 wherein said step of creatingsaid master further comprises the step of ion beam milling certain partsof said cured photopolymer to form additional optical elements therein.24. A method for creating an optical waveguide according to claim 19wherein said master is comprised of metal.
 25. A method for creating anoptical waveguide according to claim 21 wherein after the uncurled partsof said liquid photopolymer have been removed said master iselectroplated with metal to create a metal master.
 26. A method forcreating an optical waveguide according to claim 19 wherein saidembossed optical waveguide is generated by placing a layer of liquidphotopolymer in contact with said master, exposing said liquidphotopolymer to curing radiation which cures the liquid photopolymer,and separating said cured photopolymer from said master, said curedphotopolymer corresponding to said polymer material.
 27. A method forcreating an optical waveguide according to claim 26 wherein prior toexposing said layer of liquid photopolymer to curing radiation, saidsubstrate is placed in contact with said layer of liquid photopolymersuch that during exposure of said liquid photopolymer to the curingradiation, said substrate bonds to the cured layer of photopolymer. 28.A method for creating an optical waveguide according to claim 19 whereinsaid step of creating said master comprises the step of exposing apolymeric resist to a pattern of exposing radiation, wherein the patternof exposure of said resist alters its solubility in a developingsolution, wherein a pattern of resist is subsequently removed bydevelopment to thereby form said at least one optical element in saidmaster.
 29. A method for creating an optical waveguide according toclaim 28 wherein said step of creating said master further comprises thestep of reactively ion etching certain parts of said photoresist to formadditional optical elements therein.
 30. A method for creating anoptical waveguide according to claim 28 wherein said step of creatingsaid master further comprises the step of ion beam milling certain partsof said photoresist to form additional optical elements therein.
 31. Amethod for creating an optical waveguide according to claim 28 whereinafter the pattern of photoresist has been developed said master iselectroplated with metal to create a metal master.